[理工] [離散]-排列組合
(a) How many even integers in {100 ~ 999} have no two digits the same?
(i.e., every digit is different)
(b) How many numbers must be selected from the set {1,3,5,...,25} to guarantee
that at least one pair of these numbers add up to 30?
請問這兩小題怎麼解?
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◆ From: 118.160.185.25
※ 編輯: woncho 來自: 118.160.185.25 (03/04 22:39)
推
03/04 22:41, , 1F
03/04 22:41, 1F
→
03/04 22:43, , 2F
03/04 22:43, 2F
推
03/04 22:45, , 3F
03/04 22:45, 3F
→
03/04 22:45, , 4F
03/04 22:45, 4F
→
03/04 22:46, , 5F
03/04 22:46, 5F
→
03/04 22:47, , 6F
03/04 22:47, 6F
→
03/04 22:49, , 7F
03/04 22:49, 7F
推
03/04 22:49, , 8F
03/04 22:49, 8F
→
03/04 22:51, , 9F
03/04 22:51, 9F
推
03/04 22:52, , 10F
03/04 22:52, 10F
→
03/04 22:53, , 11F
03/04 22:53, 11F
→
03/04 22:54, , 12F
03/04 22:54, 12F
推
03/04 23:01, , 13F
03/04 23:01, 13F
推
03/04 23:18, , 14F
03/04 23:18, 14F
推
03/04 23:20, , 15F
03/04 23:20, 15F
推
03/04 23:31, , 16F
03/04 23:31, 16F
推
03/04 23:35, , 17F
03/04 23:35, 17F
推
03/04 23:39, , 18F
03/04 23:39, 18F
推
03/04 23:40, , 19F
03/04 23:40, 19F
推
03/04 23:43, , 20F
03/04 23:43, 20F
→
03/04 23:54, , 21F
03/04 23:54, 21F
→
03/04 23:55, , 22F
03/04 23:55, 22F
推
03/05 00:06, , 23F
03/05 00:06, 23F
→
03/05 00:06, , 24F
03/05 00:06, 24F
推
03/05 00:25, , 25F
03/05 00:25, 25F
→
03/05 00:28, , 26F
03/05 00:28, 26F
→
03/05 00:32, , 27F
03/05 00:32, 27F
推
03/05 00:33, , 28F
03/05 00:33, 28F
推
03/05 00:43, , 29F
03/05 00:43, 29F
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